   (let [env (interpret (parse "isla is a person\nfriend is isla\nisla age is 1")
                        (library/get-initial-env extra-types))]
     (is (= (resolve- {:ref "friend"} env)
-           (new isla.test.interpreter.Person 1 "" :undefined #{})))))
+           (new-person 1)))))
 
 (deftest test-lookup-resolves-object-slot-to-object-reference-with-updated-data
   (let [env (interpret (parse "isla is a person

  (let [result (interpret (parse "isla is a person")
                          (library/get-initial-env extra-types))]
    (is (= (get (:ctx result) "isla")
           (new isla.test.interpreter.Person 0 "" :undefined #{})))))

(deftest test-unknown-type-causes-exception
  (try
    (interpret (parse "isla is a giraffe")
               (library/get-initial-env extra-types))
    (is false) ;; should not get called
    (catch Exception e
      (is (= (.getMessage e) "I do not know what a giraffe is.")))))

;; slot assignment


                               isla age is 1")
                       (library/get-initial-env extra-types))]
    (is (= (resolve- {:ref "mary"} env)
           (let [isla (new-person 1)]
             (new-person 0 "" isla))))))

;; invocation

